Dark Matter in Groups and Clusters of Galaxies

Einasto, J.; Einasto, M.

doi:10.1017/s0252921100055299

Cited by 3 publications

(2 citation statements)

References 58 publications

(57 reference statements)

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“…One of the most important problems today in cosmology is the nature of dark matter and dark energy that must dominate the matter content of the Universe [1]. The existence of dark matter is suggested by the anomalies in the dynamics of galaxies and clusters of galaxies [2]. Dark energy seems to be an inevitable consequence of the present acceleration of the Universe as indicated by the type Ia supernovae (SNe Ia) data, which asks for a fluid of negative pressure which does not agglomerate at small scales [3,4].…”

Section: Introductionmentioning

confidence: 99%

BAYESIAN STATISTICS AND PARAMETER CONSTRAINTS ON THE GENERALIZED CHAPLYGIN GAS MODEL USING SNeIa DATA

Colistete

Fabris

Gonçalves

2005

Int. J. Mod. Phys. D

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The type Ia supernovae (SNe Ia) observational data are used to estimate the parameters of a cosmological model with cold dark matter and the generalized Chaplygin gas model (GCGM). The GCGM depends essentially on five parameters: the Hubble constant, the parameterĀ related to the velocity of the sound, the equation of state parameter α, the curvature of the Universe and the fraction density of the generalized Chaplygin gas (or the cold dark matter). The parameter α is allowed to take negative values and to be greater than 1. The Bayesian parameter estimation yields α = −0.86 −0.62 , where t0 is the age of the Universe and q0 is the value of the deceleration parameter today. Our results indicate that a Universe completely dominated by the generalized Chaplygin gas is favoured, what reinforces the idea that the this gas may unify the description for dark matter and dark energy, at least as the SNe Ia data is concerned. A closed and accelerating Universe is also favoured. The traditional Chaplygin gas model (CGM), α = 1 is not ruled out, even if it does not give the best-fitting. Particular cases with four or three independent free parameters are also analysed. PACS number(s): 98.80. Bp, 98.80.Es, 04.60.Gw

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Section: Introductionmentioning

confidence: 99%

BAYESIAN STATISTICS AND PARAMETER CONSTRAINTS ON THE GENERALIZED CHAPLYGIN GAS MODEL USING SNeIa DATA

Colistete

Fabris

Gonçalves

2005

Int. J. Mod. Phys. D

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“…However, at the inner region of galaxies, baryonic components such as bulge and disk are also gravitationally dominant, and dissipation processes among the baryons are important. On the other hand, since clusters of galaxies are formed only recently, the baryonic component distributes broadly as gas (Rees & Ostriker 1977) and the radial distribution of gas mass is similar to the total mass (Einasto & Einasto 2000). Hence, in order to study strong gravitational lensing without the need to include the gravitational effects of baryonic components, we shall mainly concentrate on clusters of galaxies as the lens objects and look for large-separation images (the effect of baryons on lensing was studied in (Porciani & Madau 2000, Kochanek & White 2001, Keeton 2001)).…”

Section: Introductionmentioning

confidence: 99%

Gravitational Lens Statistics and the Density Profile of Dark Halos

Takahashi

Chiba

2001

ApJ

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We investigate the inÑuence of the inner proÐle of lens objects on gravitational lens statistics, taking into account the e †ect of magniÐcation bias and both the evolution and the scatter of halo proÐles. We take the dark halos as the lens objects and consider the following three models for the density proÐle of dark halos : the SIS (singular isothermal sphere) proÐle, the NFW (Navarro-Frenk-White) proÐle, and the generalized NFW proÐle, which has a di †erent slope at smaller radii. The mass function of dark halos is assumed to be given by the Press-Schechter function. We Ðnd that magniÐcation bias for the NFW proÐle is an order of magnitude larger than that for SIS. We estimate the sensitivity of the lensing probability of distant sources to the inner proÐle of lenses and to the cosmological parameters. It turns out that the lensing probability is strongly dependent on the inner density proÐle as well as on the cosmological constant. We compare the predictions with the largest observational sample, the Cosmic Lens All-Sky Survey. The absence or presence of large splitting events in larger surveys currently underway, such as the Two Degree Field system survey and the Sloan Digital Sky Survey, could set constraints on the inner density proÐle of dark halos.

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Observation of the new emission line at ~3.5 keV in X-ray spectra of galaxies and galaxy clusters

Iakubovskyi¹

2016

Adv.Astron.Spa.Physics

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The detection of an unidentified emission line in X-ray spectra of cosmic objects would be a 'smoking gun' signature for particle physics beyond the Standard Model. More than a decade of its extensive searches results in several narrow faint emission lines reported at 3.5, 8.7, 9.4 and 10.1 keV. The most promising of them is the emission line at ∼3.5 keV reported in spectra of several nearby galaxies and galaxy clusters. Here I summarize its up-to-date status, overview its possible interpretations, including an intriguing connection with radiatively decaying dark matter, and outline future directions for its studies.

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Dark Matter in Groups and Clusters of Galaxies

Cited by 3 publications

References 58 publications

BAYESIAN STATISTICS AND PARAMETER CONSTRAINTS ON THE GENERALIZED CHAPLYGIN GAS MODEL USING SNeIa DATA

BAYESIAN STATISTICS AND PARAMETER CONSTRAINTS ON THE GENERALIZED CHAPLYGIN GAS MODEL USING SNeIa DATA

Gravitational Lens Statistics and the Density Profile of Dark Halos

Observation of the new emission line at ~3.5 keV in X-ray spectra of galaxies and galaxy clusters

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